Characteristics of the treated calcium carbonate particles with stearic acid using different treating methods.

Abstract

Calcium carbonate (CaCO3) is often treated with stearic acid (SA) to decrease its polarity. However, the method of application of the SA treatments has a strong influence on their interface structure and distribution. Several of papers describe the promising effects of SA surface treatment, but few compare the treatment process and its effect on the properties of the final composite. In the current study, we assessed a new SA treatment method, namely, combination treatment for polymer composite fabrication with HDPE. Subsequently, a comparative study was performed between the “combination” process and the other existing methods. The composites were assessed using different experiments included scanning electron microscopy (SEM), void content, density, wettability, differential scanning calorimetry (DSC), and tensile tests. It was observed that the “combination” surface treatment yielded composites with a significantly lower voids content and higher density compared to other surface treatments. This indicates that the “combination” treatment process can bring the CaCO3 particles and HDPE matrix much closer together than other methods. DSC and wettability results suggest that the “wet” and “combination” treated CaCO3 composites had a significantly higher heat of fusion and moisture resistance compared to the “dry” treated CaCO3 composites. Furthermore, “wet” and “combination” treated CaCO3 composites have a significantly higher tensile strength than the composites containing untreated and “dry” treated CaCO3. This is mainly because the “wet” and “combination” treatment processes have increased adsorption density of stearate, which enhances the interfacial interaction between matrix and filler. These results confirm that the chemical adsorption of the surfactant ions at solid-liquid interface is higher than at other interface. From this study it was concluded that the utilization of the “combination” method minimised the negative effects of void coalescence should provide key information for the improvement of existing processes.